A cold cathode fluorescent flap lamp is a light-illuminating device applied in all kinds of fields in our life. Please refer to FIG. 1 which is a schematic diagram illustrating a cross-sectional view of a conventional cold cathode fluorescent flat lamp. An enclosure chamber of the cold cathode fluorescent flat lamp is sealed by two reciprocally parallel plates of glass 13. The enclosure chamber is filled with a gas 14 selected from a group consisting of inert gas, mercury gas, and a mixing gas thereof. Preferably, the inert gas can be a helium gas, a neon gas, an argon gas, a krypton gas, a xenon gas, or a mixing gas thereof. By being provided with a voltage for an anode 11 and a cathode 12, the electrons emitting from the cathode 12 collide with the gas molecules contained in the enclosure chamber in such a way that a plasma is produced. Because of the energy difference between the exciting states and the ground states of the gas molecules, an ultraviolet light is produced when the gas molecules release the energy from the exciting states thereof to the ground states thereof. As a result, a visible light is produced when a fluorescent substance coated on the surfaces of the plates of glass 13 is illuminated with the ultraviolet light.
However, the surfaces of the electrodes, especially the cathode 12, produced according to the prior arts are very rough and plural protruding points 121 are formed thereron. Certainly, the electrons are easy to be emitted from the protruding points 121 and therefore the ions of the plasma with positive charge easily aggregate around the cathode 12. Extraordinarily, in the end, because of aggregation of the ions with positive charge around the cathode 12, the electrons are not easy to be emitted from the protruding points 121. Consequently, such a phenomenon induces a charging/discharging effect of the cathode 12. The induced charging/discharging effect will result in the light-vibration problem and lower the illumination brightness uniformity of the cold cathode fluorescent flat lamp.
Even if a further step of electropolish can be included into the method of processing the cathode to smooth the surface thereof, the electrons are still easy to be emitted from the two opposite ends 122 of the cathode 12. On the other hand, adding a step of electropolish not only increases the manufacturing cost of the cathode but also results in the problem of environmental pollution.
Accordingly, it is attempted by the present applicant to overcome the above-described problems encountered in the prior arts.